The application of mass spectrometry to the study of biological molecules has revolutionized many aspects of biomedical research. A group of thirty NIH-supported research groups located at UMDNJ-Robert Wood Johnson Medical School and Rutgers, the State University of New Jersey (Piscataway/New Brunswick Campus) are requesting an Applied Biosystems 4700 Proteomics Analyzer MALDI TOF TOF mass spectrometer to replace and upgrade our existing shared MALDI-TOF mass spectrometry resource. The user group members propose to use this instrument to perform biomedically relevant proteomics studies, protein identification, quality control of recombinant proteins, peptides, and bioconjugates, characterization of post-translational and chemical modifications, cross-linking analysis, deuterium exchange, as well as physical and structural biology studies. Most members of the User Group currently employ mass spectrometry as an integral part of their research and require continued access to a MALDI mass spectrometer, and would benefit immensely from the increased capabilities of the requested instrument. This would result in significant increases in productivity. More importantly, this resource will allow the investigators to expand their research in new directions, and to begin new projects that could not have previously been undertaken.